K.S.ViswanathamGeoscientistBGR-Sana’a

Water Harvesting in Yemen

• Water Harvesting refers to collection and storage of rainwater and also other activities aimed at harvesting surface and groundwater, prevention of losses through evaporation and seepage and all other hydrological studies and engineering interventions aimed at conservation and efficient utilization of limited water endownment of a physiographic unit such a watershed.

Definition of Water Harvesting

Water Harvesting Methods

•

CatchmentsSlopes

Roof Top

StorageUnderground storageCistern

Storage above Ground

Pond

Micro CatchmentsContour bunds and catchment strips Half-moon micro catchments

Rainwater harvesting using a road catchment

Planting pits in combination with stone lines

Micro Catchments Negarim

Contour bunds

Meskat

The Tunesian "Meskat" micro catchment system. Source: Adapted from El Amami 1983

MacrocatchmentsGully Stabilization using Gabion and loose-rock check dams

RAIN WATER HARVESTING THROUGH GABION STRUCTURE

Schematic layouts of the traditional spate irrigation in Yemeni wadis (Oosterman, 1986)

Flood Water Harvesting

Methods of Rainwater Harvesting• Insitu Harvesting:Tanka,:Land Filled Reservoirs-

Ponds, Roof Top Collection,• Hill top collection• Storage of Water in aquifers :Percolation Tanks,

Check Dams, Subsurface• Dams, Injection Wells• Soil Conservation Methods: Gully Plugging,

Contour Bonding, Trenching• Afforestation, etc• Enhancement of Runoff Collection: Catchments

Treatment• Evaporation Control: Chemical Films,

Application of polymers to soil

Urban Water harvesting

Urban Water Harvesting

Roof Top Rainwater Harvesting Measures:

In the present scenario of water particularly in Sana’a and other urban, peri-urban areasthere is a need to focus on Rainwater Harvesting particularly in urban areas through roof Top Harvesting.

Roof Top Rainwater Harvesting Measures Contd.

• Rainwater Collected From Roof and Stored Underground or in Storage tanks –

• Scarcity Period• Why Is it Required?• To meet Increasing Demand for Water in Urban

Areas• Reduce Runoff –Choking the storm Drains• To avoid flooding of the roads• To augment the groundwater storage and

control decline of water levels• (Recharge the aquifers)• To improve quality of water• To reduce soil erosion

Artificial Recharge Water Spreading and Pit Methods

Recharge Trench

Technique:• Simple• Practicable• Cost Effective• User Friendly• Socially Acceptable• Adopted in Many Countries

Rain Water Harvesting-Artificial Recharge:

• There are Direct, Indirect and Combination of methods for artificial recharge.

• The Rainwater could be used by surface spread techniques and flooding.

• The subsurface techniques include Injection wells; Gravity head recharge wells, Percolation Tanks

• Subsurface dams and Farm Ponds. The Roof Top Catchment Techniques are now very popular in many states particularly in Andhra Pradesh, Karnataka , Rajasthan India and practiced in Yemen since long

Rain Water Harvesting for Drinking Water-Urban and Peri Urban Areas:

• Utilization of Dried up wells• Water Spreading and Longitudinal

Trenches• Percolation through Pits• Shafts for Recharge

Converting existing defunct bore well into recharge bore well

Siphoning of water into operatingborewell from roof water,K arnatka,India

Open well for artificial recharge

Recharge pit constructed in Bidar district.Karnataka, India

Gabion structure-Check Dam• This is a kind of check dam commonly

constructed across small streams to • conserve stream flows with practically

no submergence beyond stream course.

• A small bund across the stream is made by putting locally available boulders in a mesh of steel wires and anchored to the stream banks.

• The height of such structures is around 0.5 m and is normally used in the

• streams with width of less than 10 m. • The excess water over flows this structure

storing some water to serve as • source of recharge. The silt content of

stream water in due course is deposited • in the interstices of the boulders in due

course and with growth of vegetation, •

RAIN WATER HARVESTING THROUGH PERCOLATION TANK –Artificial recharge

Percolation Tanks• Percolation tank is an artificially created

surface water body, submerging in its • reservoir a highly permeable land so that

surface runoff is made to percolate • and recharge the ground water storage. • Percolation tank should be constructed

preferably on second to third order • . •

• steams, located on highly fractured and weathered rocks, which have lateral

• continuity down stream. • The recharge area down stream should

have sufficient number of wells and • cultivable land to benefit from the

augmented ground water

• The percolation tanks are mostly earthen dams with masonry structure only for

• spillway. The purpose of the percolation tanks is to recharge the ground water

• storage and hence seepage below the seat of the bed is permissible. For dams

• upto 4.5 m height, cut off trenches are not necessary and keying and benching between the dam seat and the natural ground is sufficient.

Rainwater Harvesting –Bankur Village, Gulbarga District, Karnataka, India

Mukalla Traditional Irrigation Practices-

Traditional Irrigation channel-Ghayal Bawazir

Traditional Irrigation System(TIS) -Channels in Limestone Ghayl Bawazir area, Mukalla

Traditional Irrigation channel-Ghayal Bawazir

A shaft in Limestone- TIS

Al-Hajer area spring

Panoromic View of Wadi Hajer

A large "Kariaf" for irrigation at Qaidoon, Hadhramout, Yemen

The different parts of Noqab in Yemen

Case Study of Hajja Rainwater Harvesting

• Cisterns and local water management; A qualitative geographical / socio-anthropological case study and ethnographic description from the districts of Hajja, Mabyan and Shiris, Governorate of Hajja, Yemen

• (Photos after Eirik Hovden MSc Thesis University of Bergen 2006)

• )

Cisterns and local water management; A qualitative geographical / socio-anthropological case study and ethnographic description from the districts of Hajja, Mabyan and Shiris, Governorate of Hajja, Yemen(Photos after Eirik Hovden MSc Thesis University of Bergen 2006)

Case Study of Hajja Rainwater Harvesting

Macro catchments• Macro-catchment water harvesting systems

where the catchment area is located upstream the cultivated area, in most cases called external catchment system where overland flow is harvested.

• Spate irrigation system which depends on harvesting flood water from wadi channels. Their catchment area is larger than the other two systems.

Sayl (flood) irrigation

Sayl (flood) irrigationSupplimentary Rainwater Harvesting

• If the runoff is already gathered in a watercourse and the flood is diverted, this is called sayl (flood) irrigation in western academic sources.

• If the water is gathered from an area without a visible flood course in it, it is called supplementary rainwater harvesting.

Runoff supplementary irrigation (traditional)

• It simply consists of canals leading off a minor wadi or flood course. In the picture it can easily be seen that the terraces that directly receive the water from the canals, are much greener than the subsequent ones and those located above the canal. The intake dams are constructed to break if the flood is strong in order to ensure an amount of water that the outlet drainage capacity of the field can handle

Roof Top Harvesting

• water harvesting occurs, but to a very varying degree. Water is usually stored in the tanks originating from the piped public works systems and these can be bought and transported easily, but rarely hold more than 1-3 m3. Roof water harvesting is considered rather clean and thus reduces the need to carry water form the springs, at least during the rainy seasons.

Roof water harvesting

Runoff supplementary irrigation (traditional)

• The farmer owning the field will also own the water rights to the flood course. He has to give the next user down stream the flow of water when he has satisfied his own needs. There is practically no way to withhold more water than can be stored on top of the field by the field bund anyway. The height of the bund is usually 10-40 cm high. When the field is full the water will spill over a specific place called manshar (spillway) that is lined with rocks so erosion will not occur.

Supplementary Irrigation canals

• A very clear stone made collection canal for supplementary rainwater harvesting. The fields in the picture rely on direct rainfall, but the collection canal increases the water supply. The first terrace receiving the extra runoff is clearly greener than the others.

The beginning of a minor collection canal

• The potential water leading ability is indicated by the blue colour. The canal is very simply constructed by using rows and simple walls of stones as a guiding wall along the bare rock. When the water comes sand will partly fill the holes between the stones and make it more effective. This canal is very minor and is commonly used to guide runoff to agricultural terraces. This picture is taken in a low, eastern facing, dry area.

A major collection canal passing an aqueduct and can be seen extending upwards with a steady inclination. If collection canals are strongly built, it is common to use them as roads passing by otherwise steep sections. Here, it can easily be seen that it needs to be cleaned out and made deeper if it should convey more than a very small flow. The outer edge gets worn by people and animals

The same canal, viewing downstream, is hewn into the rock parts of the stretch. It was said to be several hundred years old.

Suriyya type cistern between Ajrama and Bayt Sh¢amah in Mabyan

• It was said to be 7-8 m deep and it is somewhat wider that that across. Note the complete absence of plastering. The inlet canal is from the middle of the bottom line of the picture leading to just to the left of the man in white. The canal has a “step” down, close to the lower edge of the photo. This detail is called ô¢ugala

Al-Qalaôa

The cistern at the quarter of Hajja city called al-Qalaôa. The cistern is empty and has just been cleaned out. The water enters through the presently closed hole at the top of the stairs

The cistern of −DhahraynThe cistern of −Dhahrayn, nearby. Both cisterns are today used by individuals for harvesting water that can be sold to tankers for about 1 USD pr m3. Officially, they are public property once donated by someone with attached management guidelines

Cisterns• Mosque cistern at Jabal

S¢id. As there is no piped water here, the cistern is still used in a traditional way. The two “tunnels” leading down to the water surface are used when descending the stairs to perform the ablution in a private setting at varying water levels.

The traditional village cisterns covered with a rock dome and owned by families

• An old qadad treated cover-structure over a cistern. Entering through a small door that can be locked, the cisterns look the same here as in Hajja. The covering structure is made with cantilevering masonry with qadad between

Private large new cisterns for qat irrigation

Private Cisterns for Qat• Medium sized new private cisterns for qat

irrigation. The cistern irrigates the qat that can be seen adjacent to it. The water is collected along the road toward the cistern and through the settlement basin in the end closest to the camera. The picture is taken during late spring before any heavy rain could fill it. The small houses are guard rooms as the crop is guarded from thieves during night, even close to villages.

• The water has to be pumped by a small portable petrol pump to irrigate all but the lowest terrace as the cistern is located at the same elevation as the terrace closest to the road. Such a cistern might cost 1.000.000 YR i.e. circa 5000 USD, but a price two to three times as much is also common. This picture shows a very well performed integration of a car road into the traditional landscape.

• Very often, walls are not resurrected and the masses that are left over from the construction, just pushed down the side. Restoration of terraces is usually only seen in conjunction with qat

Private cistern with a very large settlement basin

The runoff comes from a road

Private cistern in Mabyan

The runoff is from a public road, one can see that the water in the settlement basin is yellow of colour and quite clear in the main tank

Beyt Bows (Yemen). Stone settlement on the upland with an open-air cistern for

harvesting water

Archaeological site of Qana (Yemen)

is equipped with various types of water harvesting devices

The large reservoirs for water conservation on the acropolis of Thula (Yemen)

.

sufficient dimensions to supply water to the fields and the surrounding houses

Hababa (Yemen). The town surrounds the large cistern-basin where the water coming from the terraces of the buildings is collected. The

little building at the water's edge is a mosque with pools inside supplied with water by the big arches

Traditional Cisterns

Active Cisterns in Yemen

• Active cisterns can be found in• Beit Bawss• Hababa

Social Development Fund• According to Social Development fund

208 open cisterns, 47 closed cisterns and 22 water dams were built and 188cisterns were renovated during 2003-2006

• Pof Morena Livingstone, Professor, Architecture, University of Philidelphia : Yemen’s cisterns are a resource for times of water shortages because theirwater belongs to the community

Cisterns and rain water harvesting -decantation systems on the rock of Thula.

. Hababa (Yemen)..

Hababa (Yemen).

2 Channels south of Sana’a-Traditional wells for Artificial Recharge

Halam, Sana’a Basin

Series of small Dia wells for Groundwater recharge-Halam

Recharge well-Dumping waste-tyres

Groundwater -storage tank for selling to tankers

Underground channel connecting the series of wells

Cistern-water collected thro channel

Chairman, NWRA inspecting the Traditional Channels

Flooding of Syla

Surface Water Flow in Syla

Syla-old channel No scope for artificial recharge

Fog collection

Fog Collection• The best test sites produced almost 5

litre/ m2/day. Strong winds that destroy the collectors and the relative high costs of the water compared to trucked water from other sources, seems to limit the “take off” of the project for the time being (Schemenauer, Osses and Leibbrand 2004

Traditional Water Harvesting Marvels of India(Source : Dr.SS.Rao)

Rajasthan

Suggestions• Revive the traditional Water harvesting systems• Introduce in a big way roof top harvesting in

Sana’a, Taiz, Ibb and Dhamar• Introduce Law to make Roof Top harvesting

compulsory for all the buildingsas has been done in some of the cities in India.

* Artificial recharge thro Check dams, sub-surface dams, gabion structures across wadis and thro small dia wells in Wadis

* Introduce permeable pavements. Introduce agricultural practices which conserve water.

Awareness program --RWH

Suggestions-contd

• The advantages of water harvesting remain valid and farmers in dry areas have to utilize them if they want to be able to master the future.

• Farmers need scientific and institutional support to start new projects.

• NWRA to prepare pilot projects in some areas with donors support.(Sana’a: BaniHushaish Area, South of Sanaa Wadis, Taiz, Ibb, Hajja etc. Mukalla

• Thank you